Rootstock increases the physiological defence of tomato plants against Pseudomonas syringae pv. tomato infection.

Climate change has intensified the infection of tomato plants by pathogens such as Pseudomonas syringae pv. tomato (Pst). Rootstocks may increase plant tolerance to leaf phytopathogens. The aim of this study was to evaluate the effects of the tolerant Poncho Negro (R) tomato rootstock on physiological defence and the role of hydrogen sulfide (H2S) in susceptible Limachino (L) tomato plant responses to Pst attack. Ungrafted (L), self-grafted (L/L), and grafted (L/R) plants were infected with Pst. Rootstock increased the concentration of antioxidant compounds including ascorbate in the scion. Tolerant rootstock induced an increase of H2S in the scion, which correlated with enhanced expression of the SlAPX2 gene. A high accumulation of salicylic acid was observed in Pst-inoculated grafted L/L and L/R plants, but this was higher in L/R plants. The increase of H2S during Pst infection was associated with a reduction of ethylene in L/R plants. Our study indicates that the Poncho Negro rootstock reduced the symptoms of bacterial speck disease in the Limachino tomato plants, conferring tolerance to Pst infection. This study provides new knowledge about the impact of rootstock in the defence of tomato plants against leaf pathogens that could be used in sustainable management of tomato cultivation.

Salicylic acid differently impacts ethylene and polyamine synthesis in the glycophyte Solanum lycopersicum and the wild-related halophyte Solanum chilense exposed to mild salt stress.

This study aimed to determine the effects of exogenous application of salicylic acid (SA) on the toxic effects of salt in relation to ethylene and polyamine synthesis, and to correlate these traits with the expression of genes involved in ethylene and polyamine metabolism in two tomato species differing in their sensitivity to salt stress, Solanum lycopersicum cv Ailsa Craig and its wild salt-resistant relative Solanum chilense. In S. chilense, treatment with 125 mM NaCl improved plant growth, increased production of ethylene, endogenous salicylic acid and spermine. The production was related to a modification of expression of genes involved in ethylene and polyamine metabolism. In contrast, salinity decreased plant growth in S. lycopersicum without affecting endogenous ethylene, salicylic or polyamine concentrations. Exogenous application of salicylic acid at 0.01 mM enhanced shoot growth in both species and affected ethylene and polyamine production in S. chilense. Concomitant application of NaCl and salicylic acid improved osmotic adjustment, thus suggesting that salt and SA may act in synergy on osmolyte synthesis. However, the beneficial impact of exogenous application of salicylic acid was mitigated by salt stress since NaCl impaired endogenous SA accumulation in the shoot and salicylic acid did not improve plant growth in salt-treated plants. Our results thus revealed that both species respond differently to salinity and that salicylic acid, ethylene and polyamine metabolisms are involved in salt resistance in S. chilense.

Ricin poisoning after oral ingestion of castor beans: A case report and literature review.

INTRODUCTION: >1000 ricin poisoning cases secondary to intentional castor bean consumption have been reported in the literature since the late 1800s. The lethality of ricin poisoning after oral ingestion is determined by a few factors. CASE REPORT: We present a case that highlights the erratic absorption of ricin after accidental oral ingestion. On admission, the physical examination found a somnolent patient, with miosis, and a generalized abdominal tenderness. Her blood tests showed metabolic acidosis. Thanks to her early management, the discharge was possible three days later. DISCUSSION: The toxicity of ricin is dependent on the dose delivered and the route of the exposure. Supportive care is the mainstay of treatment. As shown in our case, early management is crucial for a good outcome.

A Stiff Person Syndrome Misdiagnosed as a Psychiatric Illness: A Case Report.

BACKGROUND: Stiff Person Syndrome (SPS) is a rare autoimmune neurological disorder which is often misdiagnosed. We report here a case of SPS with a long diagnosis delay. CASE: A 36-year-old man presented with an 11-year history of progressive stiffness and painful spasms of his both legs, with recent worsening of his condition over the last year resulting in a considerable difficulty of standing up and walking. As the patient developed phobic symptoms, he was considered as having a psychiatric illness and treated with antianxiety and antidepressant drugs. As no real improvement was observed, the patient was referred to internal medicine. Neurological examination showed paraspinal, abdominal and lower limbs muscle contraction with lumbar rigidity. These symptoms were associated to adrenergic symptoms: profuse sweating, tachycardia and high bloodpressure. Initial routine investigations revealed high blood glucose level. Polygraphic electromyographic (EMG) evaluation from paraspinal and leg muscles showed continuous motor unit activity in agonist and antagonist muscle. Electroencephalography and brain magnetic resonance imaging were normal. Immunologic tests according to radio immune assay technique revealed high level of serum anti-glutamic acid decarboxylase (anti-GAD65) antibodies. Diagnosis of autoimmune SPS was retained based on clinical, electrophysiological, and immunological findings. Pregabalin at the dose of 150 mg, three times a day was prescribed with satisfying response. CONCLUSION: SPS is supported by an autoimmune pathogenesis and anti-GAD antibodies seems to be very helpful when SPS is clinically suspected. Treatment of SPS is a challenge, given the scarcity of the syndrome and the absence of established recommendations.

Inhibition of ethylene synthesis reduces salt-tolerance in tomato wild relative species Solanum chilense.

Exposure to salinity induces a burst in ethylene synthesis in the wild tomato halophyte plant species Solanum chilense. In order to gain information on the role of ethylene in salt adaptation, plants of Solanum chilense (accession LA4107) and of cultivated glycophyte Solanum lycopersicum (cv. Ailsa Craig) were cultivated for 7days in nutrient solution containing 0 or 125mM NaCl in the presence or absence of the inhibitor of ethylene synthesis (aminovinylglycine (AVG) 2µM). Salt-induced ethylene synthesis in S. chilense occurred concomitantly with an increase in stomatal conductance, an efficient osmotic adjustment and the maintenance of carbon isotope discrimination value (Δ13C). In contrast, in S. lycopersicum, salt stress decreased stomatal conductance and Δ13C values while osmotic potential remained higher than in S. chilense. Inhibition of stress-induced ethylene synthesis by AVG decreased stomatal conductance and Δ13C in S. chilense and compromised osmotic adjustment. Solanum chilense behaved as an includer and accumulated high amounts of Na in the shoot but remained able to maintain K nutrition in the presence of NaCl. This species however did not stimulate the expression of genes coding for high-affinity K transport but genes coding for ethylene responsive factor ERF5 and JREF1 were constitutively more expressed in S. chilense than in S. lycopersicum. It is concluded that ethylene plays a key role in salt tolerance of S. chilense.

Phytohormone profiling in relation to osmotic adjustment in NaCl-treated plants of the halophyte tomato wild relative species Solanum chilense comparatively to the cultivated glycophyte Solanum lycopersicum.

A holistic approach was used to investigate the hormonal profile in relation with osmotic adjustment under salinity in Solanum lycopersicum and its halophyte wild relative Solanum chilense. Plants were subjected to 125mM NaCl for 7days. Solanum chilense displayed a contrasting behaviour comparatively to S. lycopersicum, not only for mineral nutrition, but also regarding the modalities of osmotic adjustment and phytohormonal profiling. The extent of osmotic adjustment was higher in S. chilense than in S. lycopersicum. Ions K+ and Na+ were the major contributors of osmotic adjustment in S. chilense, accounting respectively for 47 and 60% of osmotic potential. In contrast the contributions of proline and soluble sugars remained marginal for the two species although salt-induced accumulation of proline was higher in S. lycopersicum than in S. chilense. Both species also differed for their hormonal status under salinity and concentrations of most hormonal compounds were higher in S. chilense than in S. lycopersicum. Interestingly, salicylic acid, ethylene and cytokinins were positively correlated with osmotic potential in S. chilense under salinity while these hormones were negatively correlated with osmotic adjustment in S. lycopersicum. Our results suggested that the capacity to use inorganic ions as osmotica may improve salt resistance in S.chilense and that phytohormones could be involved in this process.

The Solanum lycopersicum WRKY3 Transcription Factor SlWRKY3 Is Involved in Salt Stress Tolerance in Tomato.

Salinity threatens productivity of economically important crops such as tomato (Solanum lycopersicum L.). WRKY transcription factors appear, from a growing body of knowledge, as important regulators of abiotic stresses tolerance. Tomato SlWRKY3 is a nuclear protein binding to the consensus CGTTGACC/T W box. SlWRKY3 is preferentially expressed in aged organs, and is rapidly induced by NaCl, KCl, and drought. In addition, SlWRKY3 responds to salicylic acid, and 35S::SlWRKY3 tomatoes showed under salt treatment reduced contents of salicylic acid. In tomato, overexpression of SlWRKY3 impacted multiple aspects of salinity tolerance. Indeed, salinized (125 mM NaCl, 20 days) 35S::SlWRKY3 tomato plants displayed reduced oxidative stress and proline contents compared to WT. Physiological parameters related to plant growth (shoot and root biomass) and photosynthesis (stomatal conductance and chlorophyll a content) were retained in transgenic plants, together with lower Na+ contents in leaves, and higher accumulation of K+ and Ca2+. Microarray analysis confirmed that many stress-related genes were already up-regulated in transgenic tomatoes under optimal conditions of growth, including genes coding for antioxidant enzymes, ion and water transporters, or plant defense proteins. Together, these results indicate that SlWRKY3 is an important regulator of salinity tolerance in tomato.

Does Salicylic Acid (SA) Improve Tolerance to Salt Stress in Plants? A Study of SA Effects On Tomato Plant Growth, Water Dynamics, Photosynthesis, and Biochemical Parameters.

Environmental stresses such as salinity directly impact crop growth, and by extension, world food supply and societal prosperity. It is estimated that over 800 million hectares of land throughout the world are salt-affected. In arid and semi-arid regions, salt concentration can be close to that in the seawater. Hence, there are intensive efforts to improve plant tolerance to salinity and other environmental stressors. Salicylic acid (SA) is an important signal molecule for modulating plant responses to stress. In the present study, we examined, on multiple plant growth related endpoints, whether SA applied through the rooting medium could mitigate the adverse effects of salinity on tomato (Solanum lycopersicum) cv. Marmande. The latter is a hitherto understudied tomato plant from the above perspective; it is a classic variety that produces the large ribbed tomatoes in the Mediterranean and consumed worldwide. We found salt stress negatively affected the growth of cv. Marmande tomato plants. However, the SA-treated plants had greater shoot and root dry mass, leaf area compared to untreated plants when exposed to salt stress. Application of SA restores photosynthetic rates and photosynthetic pigment levels under salt (NaCl) exposure. Leaf water, osmotic potential, stomatal conductance transpiration rate, and biochemical parameters were also ameliorated in SA-treated plants under saline stress conditions. Overall, these data illustrate that SA increases cv. Marmande tomato growth by improving photosynthesis, regulation and balance of osmotic potential, induction of compatible osmolyte metabolism, and alleviating membrane damage. We suggest salicylic acid might be considered as a potential growth regulator to improve tomato plant salinity stress resistance, in the current era of global climate change.